The present invention relates to a system for the formation and guidance of a radiation field of one or more solid or semiconductor lasers, especially a radiation field of an array or field arrangement of one or more solid lasers or semiconductor lasers, with a radiation transformation optic for producing a defined radiation field, wherein the optic has refractive elements. The invention furthermore relates to a method for forming and guiding a radiation field of one or more solid lasers or semiconductor lasers, especially a radiation field of an array or field arrangement of one or more solid and/or semiconductor lasers having a radiation transforming optic to produce a defined radiation field, the optic having refractive elements.
Solid and semiconductor lasers have found increasing use in the machining of materials and in medical technology.
One broad application of solid lasers is in the machining of materials. The range of the application of solid lasers is established by the required wavelength of the radiation, the power, and the shape of the lasers for the particular application. Since high beam qualities can be produced with solid lasers, especially in low-power classes, which in conjunction with short wavelengths and appropriate machining optics permit very small focal point diameters, applications of solid lasers are possible especially in the case of hard-to-machine and highly reflective materials, and in applications in which high machining precision is required. Another advantage to be mentioned is the great frequency bandwidths of solid lasers, in which many modes vibrate simultaneously, in contrast for example to gas lasers. An additional feature of a solid laser is its small size, typically about 8 cm long with a typical diameter of 1 cm. Applications of solid lasers in the field of metal machining include material ablation, boring, cutting, seaming and welding.
In recent years diode lasers have experienced rapid development. Typical applications are the machining of materials as well as the pumping of solid-state lasers.
High-power laser diodes typically possess active media with a cross section of 1 .mu.m.times.100 .mu.m. On account of the geometry of the active medium, the radiation which is yielded by the diode lasers is characterized by an elliptical beam cross section, great divergence in the narrow direction and relatively great divergence in the broad direction known as the junction plane. In order to achieve higher power densities with diode lasers it is common to combine several laser diodes into laser diode fields or arrays and focus their radiation. For the production of radiation fields, laser diodes, if they are arranged in a row, are disposed with the long axis of their elliptical beam cross sections running parallel to one another. Since the beam quality in the narrow direction is limited by diffraction and is about 1,000 times more limited by diffraction in the junction plane, the radiation emitted by a laser diode array cannot be focused to a small, circular spot with cylindrical optics and spherical optics or a combination thereof, which limits its application to, for example, the injection of the radiation into an optical fiber or to the so-called "end-on pumping" of solid lasers in conjunction with a laser diode array.
Even in the above-mentioned solid lasers, especially those of a low-power class using their high radiation qualities, it is also necessary, in order to produce expanded radiation fields with a high power density, to combine several such solid lasers into arrays or fields.
A problem which occurs in the case of large field arrays of solid lasers and diode lasers is the removal of the heat formed by lasing, which then requires appropriate cooling measures, so that spaces must be left between the individual solid lasers or active media, in order to provide heat sinks or build cooling channels for carrying cooling fluids. Such cooling of course greatly limits the pack density with which the lasers can be combined into laser arrays or fields.
For such radiation fields which are produced from arrays or field arrangements composed of diode lasers or solid lasers, since certain beam geometries and power densities are required in the imaging plane, i.e., on the workpiece surface for example, the radiation put out by each individual solid laser or diode laser must be appropriately guided and shaped.
On account of the extremely different beam qualities produced by such diode arrays in the two different directions, i.e., on account of the diffraction-limited beam quality in the narrow direction and the thousand times more diffraction-limited beam quality in the junction plane, the radiation emitted by a laser diode array cannot be focused with cylindrical optics and spherical optics or a combination of such optical components into a small, circular spot. Consequently at the present time the applications of high-power diode lasers are limited to areas where beam quality requirements are not strict. The expansion of the present-day applications to fields such as medical technology and machining, fiber optics and end-on pumping of solid and fiber lasers calls for the transformation of high-power diode laser radiation.
The same applies to the above-mentioned solid lasers of high beam quality whenever the large radiation fields that are required are to be produced from such individual solid lasers.
Setting out from the above-given state of the art and the problems described, the present invention is addressed to the problem of providing an apparatus and a process with which the radiation put out by diode and solid lasers, i.e., from diode laser or solid laser arrays composed of these lasers, or else the radiation that is put out by a laser, a diode bar for example (divided accordingly into radiation fractions), can be transformed by simple measures at moderate cost into radiation fields of any desired arrangement and power density distribution.